The present invention relates to lever switch for detecting a recording medium or a movement of a mechanism in various electronic apparatuses.
A lever switch is used for detecting a recording medium or a movement of a mechanism in various electronic apparatus. Among various types of lever switches, a leaf-switch is well-known in the market. The leaf switch includes a movable contact and a fixed contact, and both of the contacts are made of elastic and thin metal plates facing each other via a given space. The contacts contact with each other by rotating a lever.
A conventional lever switch as discussed above is described with reference to FIG. 10 and FIG. 11. FIG. 10 is a sectional view of the conventional lever switch. Box-shaped case 1 made of insulating resin opens frontward and has opening 1A on the left side. Lever 2 is rotatably held by case 1 at shaft section 2A. A first end of lever 2, i.e., driving section 2A, is housed in case 1, and a second end, i.e., handle section 2C, protrudes out of opening 1A upward slantingly. Movable contact 3 and fixed contact 4, both being made of elastic and thin metal plate, are rigidly mounted to side-wall 1B opposite to opening 1A. An end of movable contact 3 elastically contacts with an upper face of driving section 2B, and moves handle section 2C upward slantingly. Contact section 4A slightly bowed downward is provided to an end of fixed contact 4 opposite to an intermediate portion of movable section 3. A front face of case 1, which accommodates movable contact 3 and fixed contact 4, is covered with a cover (not shown). Lever 2 is rotatably held at shaft section 2A.
As shown in FIG. 11, when handle section 2C of lever 2 is rotated downward, driving section 2B rotates and moves upward on shaft section 2A as a fulcrum and pushes up the left end of movable contact 3. This action bends movable contact 3, and brings the intermediate portion into contact with contact section 4A of fixed contact 4.
When handle section 2C rotates by a given stroke, the end of movable contact 3 further moves upward, which bends fixed contact 4 upward, so that movable contact 3 may contact with fixed contact 4 by a stable contact pressure.
When operating-force applied to handle section 2C is released, driving section 2B is depressed downward by elastic restoring force of movable contact 3 and fixed contact 4, and lever 2 rotates and handle section 2C returns to the status shown in FIG. 10.
In the conventional lever switch discussed above, movable contact 3 contacts with contact section 4A of fixed contact 4 by rotating handle section 2C of lever 2. Then, lever 2 is further rotated to bend fixed contact 4, thereby obtaining a stable contact pressure between movable contact 3 and fixed contact 4. However, the contact remains unstable before lever 2 completes its rotation.
The present invention aims to provide a lever switch which assures stable contact just after both contacts touch with each other. The lever switch includes the following elements:
(a) a case including a first side-wall, a second side-wall adjacent to the first side-wall, and a third side-wall having an opening;
(b) a common contact provided to the first side-wall;
(c) a first fixed contact provided to the second side-wall;
(d) a supporting protrusion disposed around the common contact in the case;
(e) a lever including:
a shaft section rotatably held at the opening and being disposed at an intermediate portion of the lever;
a driving section housed in the case and disposed at a first end of the lever; and
a handle section protruded from the opening outside the case and disposed at a second end of the lever,
(f) an elastic movable contact, being formed in an approximate V-shape, including:
a bent section housed in the case with the driving section touched around the bent section, and the bent section being disposed at an intermediate portion of the movable contact;
a first arm extending from a first side of the bent section;
a fixed section, being formed in an approximate square U-shape, provided to a tip of the first arm and fixed between the common contact and the supporting protrusion;
a second arm extending from a second side of the bent section; and
a contact section being provided at a tip of the second arm and elastically contacting with both the first fixed contact and the second side-wall.
The contact section of the movable contact, which is slightly bent, elastically slides on the side-wall of the case or on the fixed contact, thereby touching or leaving the fixed contact. Therefore, even while the lever is rotating, the movable contact is kept in contact with the fixed contact by a constant pressure.